In biofuel power plants, quality fluctuations can bring challenges to everyday operations in addition to causing additional costs. The new measurement system utilising x-ray technology enables real-time fuel quality monitoring. For example the system detects fuel moisture fluctuations and can also recognise foreign objects such as stones and metals. UPM Caledonian's biofuel power plant in Great Britain uses this measurement system to improve the plant's energy efficiency.

Fuel quality fluctuations present a challenge to biofuel power plants

Biofuel power plant fuels may contain 15-80% water and as much as a fifth is non-combustible materials. The energy content of a load can even be lower than the amount of energy used to process and transport the load. These poor-quality loads challenge the operations at the power plant. In Britain, winters are rainy and humid. This also reflects on the quality of wood chips. Alongside damp wood chips, recovered wood is often used as fuel. It is usually dry but contains a high amount of foreign materials.

From sampling to real-time measurement

With the current quality assurance method, samples are collected from the fuel load for subsequent laboratory analysis. However, due to the difficulty in obtaining representative samples using this method, as well as the slowness of the process, the load is already being incinerated before the analysis of its contents is available.

The fuel quality analysis method based on x-ray technology measures the fuel moisture, volume and foreign material content in each load in real time. This method enables an analysis of the fuel load energy content immediately after unloading. As real-time quality information is readily available to the power plant, it is easier to take preventive measures regarding poor-quality fuels and reduce the additional costs incurred.

Development funded by European Commission

The EU has set itself ambitious energy and climate targets for the years ahead. The goal is to reduce greenhouse gas emissions, increase the percentage of renewable energy sources used for energy consumption and to improve energy efficiency. In its attempt to reach these goals, the EU is financing small and medium-sized enterprises who are both seeking international growth and have the ability to provide solutions for reducing emissions and improving energy efficiency. The European Commission granted a Finnish company Inray Oy approximately 1.2 million euros for the development of the OPTIFUEL system based on x-ray technology. The source of funding is Horizon 2020's SME instrument, providing approximately 3 billion euros in funding between 2014 and 2020. UPM Caledonian's biofuel power plant will employ the Inray system in 2017 and 2018.

Previous experience from UPM Kaipola power plant

UPM has tested the same technology at the UPM Kaipola power plant for some years now. The system has been in continuous use since 2015 and another system was installed in the spring of 2016. Load-specific quality measurement has improved fuel quality, decreased fuel moisture and the ratio of non-combustible materials as well as improved efficiency and decreased maintenance costs at the power plant.